Method for calibrating mass flow controllers in a printing apparatus for dispensing a liquid composition on a backplane

Abstract

A method for calibrating liquid flow measurements in a printing apparatus that includes a liquid flow line having a flow meter therein comprises the steps of: (a) using a positive displacement liquid pump operable while connected in fluid communication with the flow meter, pumping a liquid at a directly measured, precisely dispensed flow rate through the flow meter; (b) using the flow meter, measuring the volumetric flow rate of a liquid passed through the flow meter; (c) comparing the volumetric flow rate dispensable by the pump to a volumetric flow rate measurable by the flow meter; and (d) modifying the calibration parameters of the flow meter in accordance with the flow rate dispensed from the pump.

What is claimed is: 
     
         1 . A method for calibrating liquid flow measurements in a printing apparatus for depositing a liquid on a surface, the printing apparatus itself including:
 a liquid flow line terminating in a flow nozzle;   a flow meter connected in the flow line in series with the flow nozzle, the flow meter being operable to provide a measurement of the volumetric flow rate of liquid dispensed by the nozzle, the flow meter having predetermined calibration parameters that are susceptible to measurement inaccuracies;   the method comprising the steps of:
 (a) using a positive displacement liquid pump operable while connected in fluid communication with the flow meter, pumping a liquid at a directly measured, precisely dispensed flow rate through the flow meter; 
 (b) using the flow meter, measuring the volumetric flow rate of a liquid passed through the flow meter; 
 (c) comparing the volumetric flow rate dispensable by the pump to a volumetric flow rate measurable by the flow meter; 
 (d) modifying the calibration parameters of the flow meter in accordance with the flow rate dispensed from the pump. 
   
     
     
         2 . The method of  claim 1  wherein a portion of the liquid flow line contains a flexible portion adjacent the nozzle. 
     
     
         3 . The method of  claim 1  further comprising a dispensing bar containing a set of the nozzles. 
     
     
         4 . The method of  claim 3  wherein the set of nozzles includes at least 3 sets of nozzles. 
     
     
         5 . The method of  claim 3  wherein the set of nozzles includes at least 5 sets of nozzles. 
     
     
         6 . The method of  claim 4  wherein each set of nozzles comprises: a nozzle for dispensing a liquid composition to produce a red emitting sub-pixel; a nozzle for dispensing a liquid composition to produce a green emitting sub-pixel; and a nozzle for dispensing a liquid composition to produce a blue emitting sub-pixel. 
     
     
         7 . The method of  claim 6  wherein each of the liquid compositions contains at least one organic semiconductor material. 
     
     
         8 . A method for calibrating liquid flow measurements in a printing apparatus for depositing a liquid on a surface, the printing apparatus itself including:
 a plurality of liquid flow lines, each flow line terminating in a flow nozzle;   a flow meter disposed in each flow line, each meter being connected in series with the flow nozzle in its respective flow line, each flow meter being operable to provide a measurement of the volumetric flow rate of liquid dispensed by a nozzle, each flow meter having predetermined calibration parameters that are susceptible to measurement inaccuracies;   the method comprising the steps of:
 (a) using a positive displacement liquid pump operable while connected in fluid communication with each flow meter, simultaneously pumping a liquid at a directly measured, precisely dispensed flow rate through each flow meter; 
 (b) using each flow meter, measuring the volumetric flow rate of a liquid passed through that flow meter; 
 (c) comparing the volumetric flow rate dispensable by the pump to a volumetric flow rate measurable by each meter; and 
 (d) modifying the calibration parameters of each flow meter in accordance with the flow rate dispensed from the pump. 
   
     
     
         9 . The method of  claim 8  wherein a portion of the liquid flow lines contains a flexible portion adjacent each of the nozzles. 
     
     
         10 . The method of  claim 8  further comprising dispensing bars containing a set of the nozzles. 
     
     
         11 . The method of  claim 10  wherein the set of nozzles includes at least 3 sets of nozzles. 
     
     
         12 . The method of  claim 10  wherein the set of nozzles includes at least 5 sets of nozzles. 
     
     
         13 . The method of  claim 11  wherein each set of nozzles comprises: a nozzle for dispensing a liquid composition to produce a red emitting sub-pixel; a nozzle for dispensing a liquid composition to produce a green emitting sub-pixel; and a nozzle for dispensing a liquid composition to produce a blue emitting sub-pixel. 
     
     
         14 . The method of  claim 13  wherein each of the liquid compositions contains at least one organic semiconductor material.